The present invention pertains to a method for operating a driven axle in a machine tool, in particular an injection molding machine, wherein at least two different drives are coupled into a common effective drive, as well as to a device for operating a driven axle in a machine tool.
Machine tools such as, among other things, injection molding machines typically feature several driven axles that in some instances have very high and different load ranges. In an injection molding machine, for example, the injection process, i.e., the process, in which the molten material is conveyed into the cavity of the tool, is the process with the most variable requirement. In this case, an extreme speed range and pressure range needs to be controlled depending on the respective application. Injection speeds from a few tenths of a millimeter per second up to 1 meter per second are required. With respect to the load range, the requirements may lie between less than 100 bar and more than 2,000 bar. On extreme examination, the performance requirement therefore varies by up to a factor of 20,000. If this broad scope of applications should be covered with today's conventional drive arrangements, the power cannot be made available in an energetically optimal fashion, at least not in all applications. For example, high peak powers can only be made available directly by a hydraulic pump (e.g., variable displacement or fixed displacement pump) up to a certain power limit. Beginning at a certain power limit, an intermediate storage is required (e.g., by means of a hydraulic accumulator) and the power is then obtained from such a storage.